ALTER LOCATION

Purpose

This statement is used to modify the properties of a Location object.

Privilege requirements

• Execution privilege:

  To execute the ALTER LOCATION statement, the current user must have the CREATE LOCATION privilege. For more information about privileges in OceanBase Database, see Privilege types in MySQL-compatible mode.

• Authentication credential privilege:

  The provided ACCESSID and ACCESSKEY must have valid access permissions for the target storage service.

Syntax

ALTER LOCATION location_name SET 
    {URL = 'file_path'
    | CREDENTIAL = (credential_list)
    };

credential_list:
    ACCESSID = 'string'
    ACCESSKEY = 'string'
    HOST = 'string'
    [S3_REGION = 'string']
    [PRINCIPAL = 'string']
    [KEYTAB = 'string']
    [KRB5CONF = 'string']
    [CONFIGS = 'string']
    [USERNAME = 'string']

Parameters

file_path

The path for storing external table files can be in the following formats:

• Local path: URL = '[file:// | sfile://] local_file_path'

  • file://: This protocol header indicates that when encountering files with the same logical path across multiple OBServer nodes, they are treated as different files and processed separately. Each node independently reads the file from its local path.

  • sfile://: This protocol header indicates that when encountering files with the same logical path across multiple OBServer nodes, the system performs deduplication based on the logical path to ensure only one copy of the data is read (supporting multi-server load balancing).

    Note

    • When using sfile://, the system performs consistency verification of file sizes. If files under the same logical path have inconsistent sizes across different OBServer nodes, the system reports an error OB_INVALID_EXTERNAL_FILE to avoid result errors caused by data inconsistency.
    • For version V4.4.2, starting from V4.4.2 BP2, support for the sfile:// protocol header was added to the local URL path format in the ALTER LOCATION syntax.

  • local_file_path: Can be a relative or absolute path.

• HDFS path: URL = 'hdfs://localhost:port/PATH', where localhost is the address of the HDFS cluster, port is the port number of the HDFS cluster, and PATH is the directory path in HDFS.

• Object storage (OSS/S3) path: URL = '{oss | s3}://bucket/remote_file_path'.

credential_list

• ACCESSID: the AccessKey ID of the user for accessing object storage.
• ACCESSKEY: the AccessKey secret of the user for accessing object storage.
• HOST: the host address of the object storage service.
• S3_REGION: optional. The service region of the S3 object storage.
• PRINCIPAL: optional. The login authentication user when the target HDFS cluster is in a Kerberos environment.
• KEYTAB: optional. The authentication key file path when the target HDFS cluster is in a Kerberos environment.
• KRB5CONF: optional. The file path for using Kerberos when the target HDFS cluster is in a Kerberos environment.
• CONFIGS: optional. Additional cluster configuration items when the target HDFS cluster is in a Kerberos environment.
• USERNAME: optional. The unique identifier for the user when the target HDFS cluster is in a Kerberos environment.

Examples

Modify the CREDENTIAL information of the test_location_oss Location object.

obclient> ALTER LOCATION test_location_oss SET
    CREDENTIAL = (
        ACCESSID = '******'
        ACCESSKEY = '******'
        HOST = '******'
        );

References

For information about viewing files under a Location object, see SHOW.